George Lucas decided to replace the original version of Yoda from Star Wars Episode I: The Phantom Menace with a full CG version of the character. Check out the comparison videos below.

The Original Version:

The Updated Version:

Star Wars : The Complete Saga on Blu-ray will be available for $139.99 US/$179.99 CAN and the Star Wars: Trilogy Sets for $69.99 US/89.99 CAN. Pricing for each set will vary by international territory.
(Source Comicbookmovie.com)

Update:
More footage with digital Yoda in Episode 1, including meeting with Obi-Wan, the funeral, and the Naboo celebration